2008 f250, no trailer lights but brakes work
 

I hooked up a buddy's trailer that had been in a field during a brush fire. It sustained minimal damage but some of the wiring got melted. Well now my trailer light plug has no power for any lights. The brakes work fine but no lights, not running, braking, or signals and there is no power at the plug for lights. I assumed fuse, but checked the ones that I thought they could be and they were fine.

I would assume the trailer lights shorted out and blew a fuse but I checked all of them with a test light and didn't find any blown. Any relays?

there ARE two sets of fuses.. one in the right kick panel area too.. altho I haven't seen those blow out..

is there a bad ground at the trailer plug?

Sam

Possibly, but wouldnt that affect the trailer brakes also? With a test light at the plug, there is 0 power except on the brake pin when brakes are applied.

Any idea what fuses for sure control the trailer lights? I checked all of the fuses in the.kickpanel and all the ones I thought could be right under the.hood

this manual (online copy) http://www.motorcraftservice.com
at page 300
lists all the fuses.

note there is a lamp RELAY too..

Sam

Thanks, ill take a look when I get home.

I would also suggest hooking up to a known good trailer as an easy method to check your truck and fuses.

Ya, I did use 2 separate trailers and both the bumper plug and the bed plug. Both have the same issues. Both trailers the brakes worked and.both pkugs had no lights

wait.. new news.. BED plug..

did you actually check in the wiring harness BEFORE the bed plug connection?

Sam

Both plugs worked a month or so ago before I hooked his trailer up.

understood.. no power at the plugs.. fuses seem good.. check the relays.. I think there is one you can swap.. maybe the brake relay for the light relay.
then check the connection for the bed plug..

Sam

ok, so I am JUST getting to troubleshooting this. Sam, i tried clicking on your link above and it says i do not have permission to the site and need to login again?

Does anybody know which relay is the lamp relay?

gr.. I hate that site.. I fixed the link.. then u have to pick guides in the left nav, and ...

relay 42 is trailer park lamp relay, 44 is the trailer battery charge relay

Sam

Thanks, heading out now to check it out!

Where's your owner's manual? It would have all information about fuses, relays and breakers.